<?php
class My_Controller_Admin_Action extends Zend_Controller_Action
{
    public function init()
    {
        if (!Mage::getSingleton('application/users')->isLoggedIn()) {
            $this->_redirect('admin/users');
        }
        $this->_initUser();
        $this->_init();
    }

    protected function _initUser()
    {
        Mage::getSingleton('application/users')->initUser();
    }

    protected function _init()
    {
    }
}